Monitor, to exist, and the degree to which one has become a formal thinker may relate to the success one has in formal language learning.

On the other hand, formal operations may be at least partly responsible for a fossilization of progress in subconscious language acquisition. One effect of formal operations on acquisition may be a result of what can be termed the indirect effects of formal operations, namely the affective changes that occur in adolescence that are catalyzed by formal operations. These changes result in the selfconsciousness and feelings of vulnerability often observed in this age group, Elkind (1970) has argued that formal operations allows one to conceptualize the thoughts of others-this leads the adolescent to the false conclusions that others are thinking about him and are focusing on just what he considers to be his inadequacies. Such feeling may generate at least in part attitudes unfavorable for the successful acquisition of a second language, which may act to discourage the acquirer from interacting with primary linguistic data, and/or may act to strengthen an "affective filter" (Dulay and Burt, 1977) that prevents the acquirer from utilizing all the input he hears for further language acquisition. (For more detailed discussion, see Chapter 2.)

The available data strongly suggest, however, that subconscious language acquisition is nevertheless the central means by which adults internalize second languages, a position supported not only by research but also by the practice of successful language teachers who emphasize communicative activities in the classroom (see, for example, Terrell, 1977).

To summarize to this point: Lenneberg's claim that lateralization was complete by puberty and is the neurological basis for the critical period for language acquisition and thus responsible for child-adult differences in second language acquisition is not entirely ruled out. There is, however, considerable evidence today that implies that much of the development of cerebral dominance may be complete much earlier and may have little or nothing to do with the critical period. Moreover, there are other possible "explanations" for the critical period. The one sketched above maintains that the ability to "acquire" language naturally does not disappear at puberty, a position that is consistent with current teaching practice.

77